// Copyright 2011 David Galles, University of San Francisco. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other materials
// provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ``AS IS'' AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
// ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// The views and conclusions contained in the software and documentation are those of the
// authors and should not be interpreted as representing official policies, either expressed
// or implied, of the University of San Francisco

import { Algorithm, addControlToAlgorithmBar } from "@/components/algorithm/Algorithm";

export class AVL extends Algorithm {
	constructor(am, w, h) {
		super();
		this.init(am, w, h);

	}
	init(am, w, h) {
		this.first_print_pos_y = h - 2 * AVL.PRINT_VERTICAL_GAP;
		this.print_max = w - 10;

		super.init.call(this, am, w, h);
		this.startingX = w / 2;
		this.addControls();
		this.nextIndex = 1;
		this.commands = [];
		this.cmd("CreateLabel", 0, "", AVL.EXPLANITORY_TEXT_X, AVL.EXPLANITORY_TEXT_Y, 0);
		this.animationManager.StartNewAnimation(this.commands);
		this.animationManager.skipForward();
		this.animationManager.clearHistory();

	}
	addControls() {
		this.insertField = addControlToAlgorithmBar("Text", "");
		this.insertField.onkeydown = this.returnSubmit(this.insertField, this.insertCallback.bind(this), 4);
		this.insertButton = addControlToAlgorithmBar("Button", "插入");
		this.insertButton.onclick = this.insertCallback.bind(this);
		this.deleteField = addControlToAlgorithmBar("Text", "");
		this.deleteField.onkeydown = this.returnSubmit(this.deleteField, this.deleteCallback.bind(this), 4);
		this.deleteButton = addControlToAlgorithmBar("Button", "删除");
		this.deleteButton.onclick = this.deleteCallback.bind(this);
		this.findField = addControlToAlgorithmBar("Text", "");
		this.findField.onkeydown = this.returnSubmit(this.findField, this.findCallback.bind(this), 4);
		this.findButton = addControlToAlgorithmBar("Button", "查找");
		this.findButton.onclick = this.findCallback.bind(this);
		this.printButton = addControlToAlgorithmBar("Button", "打印");
		this.printButton.onclick = this.printCallback.bind(this);
	}
	reset() {
		this.nextIndex = 1;
		this.treeRoot = null;
	}
	insertCallback(event) {
		var insertedValue = this.insertField.value;
		// Get text value
		insertedValue = this.normalizeNumber(insertedValue, 4);
		if (insertedValue != "") {
			// set text value
			this.insertField.value = "";
			this.implementAction(this.insertElement.bind(this), insertedValue);
		}
	}
	deleteCallback(event) {
		var deletedValue = this.deleteField.value;
		if (deletedValue != "") {
			deletedValue = this.normalizeNumber(deletedValue, 4);
			this.deleteField.value = "";
			this.implementAction(this.deleteElement.bind(this), deletedValue);
		}
	}
	findCallback(event) {
		var findValue = this.findField.value;
		if (findValue != "") {
			findValue = this.normalizeNumber(findValue, 4);
			this.findField.value = "";
			this.implementAction(this.findElement.bind(this), findValue);
		}
	}
	printCallback(event) {
		this.implementAction(this.printTree.bind(this), "");
	}
	sizeChanged(newWidth, newHeight) {
		this.startingX = newWidth / 2;
	}
	printTree(unused) {
		this.commands = [];

		if (this.treeRoot != null) {
			this.highlightID = this.nextIndex++;
			var firstLabel = this.nextIndex;
			this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, this.treeRoot.x, this.treeRoot.y);
			this.xPosOfNextLabel = AVL.FIRST_PRINT_POS_X;
			this.yPosOfNextLabel = this.first_print_pos_y;
			this.printTreeRec(this.treeRoot);
			this.cmd("Delete", this.highlightID);
			this.cmd("Step");
			for (var i = firstLabel; i < this.nextIndex; i++)
				this.cmd("Delete", i);
			this.nextIndex = this.highlightID; /// Reuse objects.  Not necessary.
		}
		return this.commands;
	}
	printTreeRec(tree) {
		this.cmd("Step");
		if (tree.left != null) {
			this.cmd("Move", this.highlightID, tree.left.x, tree.left.y);
			this.printTreeRec(tree.left);
			this.cmd("Move", this.highlightID, tree.x, tree.y);
			this.cmd("Step");
		}
		var nextLabelID = this.nextIndex++;
		this.cmd("CreateLabel", nextLabelID, tree.data, tree.x, tree.y);
		this.cmd("SetForegroundColor", nextLabelID, AVL.PRINT_COLOR);
		this.cmd("Move", nextLabelID, this.xPosOfNextLabel, this.yPosOfNextLabel);
		this.cmd("Step");

		this.xPosOfNextLabel += AVL.PRINT_HORIZONTAL_GAP;
		if (this.xPosOfNextLabel > this.print_max) {
			this.xPosOfNextLabel = AVL.FIRST_PRINT_POS_X;
			this.yPosOfNextLabel += AVL.PRINT_VERTICAL_GAP;

		}
		if (tree.right != null) {
			this.cmd("Move", this.highlightID, tree.right.x, tree.right.y);
			this.printTreeRec(tree.right);
			this.cmd("Move", this.highlightID, tree.x, tree.y);
			this.cmd("Step");
		}
		return;
	}
	findElement(findValue) {
		this.commands = [];

		this.highlightID = this.nextIndex++;

		this.doFind(this.treeRoot, findValue);


		return this.commands;
	}
	doFind(tree, value) {
		this.cmd("SetText", 0, "查询 " + value);
		if (tree != null) {
			this.cmd("SetHighlight", tree.graphicID, 1);
			if (tree.data == value) {
				this.cmd("SetText", 0, "查询 " + value + " : " + value + " = " + value + " (找到元素!)");
				this.cmd("Step");
				this.cmd("SetText", 0, "找到:" + value);
				this.cmd("SetHighlight", tree.graphicID, 0);
			}

			else {
				if (tree.data > value) {
					this.cmd("SetText", 0, "查询 " + value + " : " + value + " < " + tree.data + " (查询左子树)");
					this.cmd("Step");
					this.cmd("SetHighlight", tree.graphicID, 0);
					if (tree.left != null) {
						this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
						this.cmd("Move", this.highlightID, tree.left.x, tree.left.y);
						this.cmd("Step");
						this.cmd("Delete", this.highlightID);
					}
					this.doFind(tree.left, value);
				}

				else {
					this.cmd("SetText", 0, "查询 " + value + " : " + value + " > " + tree.data + " (查询右子树)");
					this.cmd("Step");
					this.cmd("SetHighlight", tree.graphicID, 0);
					if (tree.right != null) {
						this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
						this.cmd("Move", this.highlightID, tree.right.x, tree.right.y);
						this.cmd("Step");
						this.cmd("Delete", this.highlightID);
					}
					this.doFind(tree.right, value);
				}

			}

		}

		else {
			this.cmd("SetText", 0, "查询 " + value + " : " + "< 空树 > (未找到元素)");
			this.cmd("Step");
			this.cmd("SetText", 0, "查询 " + value + " : " + " (未找到元素)");
		}
	}
	insertElement(insertedValue) {
		this.commands = [];
		this.cmd("SetText", 0, "插入 " + insertedValue);

		if (this.treeRoot == null) {
			var treeNodeID = this.nextIndex++;
			var labelID = this.nextIndex++;
			this.cmd("CreateCircle", treeNodeID, insertedValue, this.startingX, AVL.STARTING_Y);
			this.cmd("SetForegroundColor", treeNodeID, AVL.FOREGROUND_COLOR);
			this.cmd("SetBackgroundColor", treeNodeID, AVL.BACKGROUND_COLOR);
			this.cmd("CreateLabel", labelID, 1, this.startingX - 20, AVL.STARTING_Y - 20);
			this.cmd("SetForegroundColor", labelID, AVL.HEIGHT_LABEL_COLOR);
			this.cmd("Step");
			this.treeRoot = new AVLNode(insertedValue, treeNodeID, labelID, this.startingX, AVL.STARTING_Y);
			this.treeRoot.height = 1;
		}

		else {
			treeNodeID = this.nextIndex++;
			labelID = this.nextIndex++;
			this.highlightID = this.nextIndex++;

			this.cmd("CreateCircle", treeNodeID, insertedValue, 30, AVL.STARTING_Y);

			this.cmd("SetForegroundColor", treeNodeID, AVL.FOREGROUND_COLOR);
			this.cmd("SetBackgroundColor", treeNodeID, AVL.BACKGROUND_COLOR);
			this.cmd("CreateLabel", labelID, "", 100 - 20, 100 - 20);
			this.cmd("SetForegroundColor", labelID, AVL.HEIGHT_LABEL_COLOR);
			this.cmd("Step");
			var insertElem = new AVLNode(insertedValue, treeNodeID, labelID, 100, 100);

			this.cmd("SetHighlight", insertElem.graphicID, 1);
			insertElem.height = 1;
			this.insert(insertElem, this.treeRoot);
			//				this.resizeTree();				
		}
		this.cmd("SetText", 0, " ");
		return this.commands;
	}
	singleRotateRight(tree) {
		var B = tree;
		var t3 = B.right;
		var A = tree.left;
		var t1 = A.left;
		var t2 = A.right;

		this.cmd("SetText", 0, "单向右旋转");
		this.cmd("SetEdgeHighlight", B.graphicID, A.graphicID, 1);
		this.cmd("Step");


		if (t2 != null) {
			this.cmd("Disconnect", A.graphicID, t2.graphicID);
			this.cmd("Connect", B.graphicID, t2.graphicID, AVL.LINK_COLOR);
			t2.parent = B;
		}
		this.cmd("Disconnect", B.graphicID, A.graphicID);
		this.cmd("Connect", A.graphicID, B.graphicID, AVL.LINK_COLOR);
		A.parent = B.parent;
		if (this.treeRoot == B) {
			this.treeRoot = A;
		}

		else {
			this.cmd("Disconnect", B.parent.graphicID, B.graphicID, AVL.LINK_COLOR);
			this.cmd("Connect", B.parent.graphicID, A.graphicID, AVL.LINK_COLOR);
			if (B.isLeftChild()) {
				B.parent.left = A;
			}

			else {
				B.parent.right = A;
			}
		}
		A.right = B;
		B.parent = A;
		B.left = t2;
		this.resetHeight(B);
		this.resetHeight(A);
		this.resizeTree();
	}
	singleRotateLeft(tree) {
		var A = tree;
		var B = tree.right;
		var t1 = A.left;
		var t2 = B.left;
		var t3 = B.right;

		this.cmd("SetText", 0, "单向左旋转");
		this.cmd("SetEdgeHighlight", A.graphicID, B.graphicID, 1);
		this.cmd("Step");

		if (t2 != null) {
			this.cmd("Disconnect", B.graphicID, t2.graphicID);
			this.cmd("Connect", A.graphicID, t2.graphicID, AVL.LINK_COLOR);
			t2.parent = A;
		}
		this.cmd("Disconnect", A.graphicID, B.graphicID);
		this.cmd("Connect", B.graphicID, A.graphicID, AVL.LINK_COLOR);
		B.parent = A.parent;
		if (this.treeRoot == A) {
			this.treeRoot = B;
		}

		else {
			this.cmd("Disconnect", A.parent.graphicID, A.graphicID, AVL.LINK_COLOR);
			this.cmd("Connect", A.parent.graphicID, B.graphicID, AVL.LINK_COLOR);

			if (A.isLeftChild()) {
				A.parent.left = B;
			}

			else {
				A.parent.right = B;
			}
		}
		B.left = A;
		A.parent = B;
		A.right = t2;
		this.resetHeight(A);
		this.resetHeight(B);

		this.resizeTree();
	}
	getHeight(tree) {
		if (tree == null) {
			return 0;
		}
		return tree.height;
	}
	resetHeight(tree) {
		if (tree != null) {
			var newHeight = Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1;
			if (tree.height != newHeight) {
				tree.height = Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1;
				this.cmd("SetText", tree.heightLabelID, newHeight);
				//			this.cmd("SetText",tree.heightLabelID, newHeight);
			}
		}
	}
	doubleRotateRight(tree) {
		this.cmd("SetText", 0, "双向右旋转");
		var A = tree.left;
		var B = tree.left.right;
		var C = tree;
		var t1 = A.left;
		var t2 = B.left;
		var t3 = B.right;
		var t4 = C.right;

		this.cmd("Disconnect", C.graphicID, A.graphicID);
		this.cmd("Disconnect", A.graphicID, B.graphicID);
		this.cmd("Connect", C.graphicID, A.graphicID, AVL.HIGHLIGHT_LINK_COLOR);
		this.cmd("Connect", A.graphicID, B.graphicID, AVL.HIGHLIGHT_LINK_COLOR);
		this.cmd("Step");

		if (t2 != null) {
			this.cmd("Disconnect", B.graphicID, t2.graphicID);
			t2.parent = A;
			A.right = t2;
			this.cmd("Connect", A.graphicID, t2.graphicID, AVL.LINK_COLOR);
		}
		if (t3 != null) {
			this.cmd("Disconnect", B.graphicID, t3.graphicID);
			t3.parent = C;
			C.left = t2;
			this.cmd("Connect", C.graphicID, t3.graphicID, AVL.LINK_COLOR);
		}
		if (C.parent == null) {
			B.parent = null;
			this.treeRoot = B;
		}

		else {
			this.cmd("Disconnect", C.parent.graphicID, C.graphicID);
			this.cmd("Connect", C.parent.graphicID, B.graphicID, AVL.LINK_COLOR);
			if (C.isLeftChild()) {
				C.parent.left = B;
			}

			else {
				C.parent.right = B;
			}
			B.parent = C.parent;
			C.parent = B;
		}
		this.cmd("Disconnect", C.graphicID, A.graphicID);
		this.cmd("Disconnect", A.graphicID, B.graphicID);
		this.cmd("Connect", B.graphicID, A.graphicID, AVL.LINK_COLOR);
		this.cmd("Connect", B.graphicID, C.graphicID, AVL.LINK_COLOR);
		B.left = A;
		A.parent = B;
		B.right = C;
		C.parent = B;
		A.right = t2;
		C.left = t3;
		this.resetHeight(A);
		this.resetHeight(C);
		this.resetHeight(B);

		this.resizeTree();


	}
	doubleRotateLeft(tree) {
		this.cmd("SetText", 0, "双向左旋转");
		var A = tree;
		var B = tree.right.left;
		var C = tree.right;
		var t1 = A.left;
		var t2 = B.left;
		var t3 = B.right;
		var t4 = C.right;

		this.cmd("Disconnect", A.graphicID, C.graphicID);
		this.cmd("Disconnect", C.graphicID, B.graphicID);
		this.cmd("Connect", A.graphicID, C.graphicID, AVL.HIGHLIGHT_LINK_COLOR);
		this.cmd("Connect", C.graphicID, B.graphicID, AVL.HIGHLIGHT_LINK_COLOR);
		this.cmd("Step");

		if (t2 != null) {
			this.cmd("Disconnect", B.graphicID, t2.graphicID);
			t2.parent = A;
			A.right = t2;
			this.cmd("Connect", A.graphicID, t2.graphicID, AVL.LINK_COLOR);
		}
		if (t3 != null) {
			this.cmd("Disconnect", B.graphicID, t3.graphicID);
			t3.parent = C;
			C.left = t2;
			this.cmd("Connect", C.graphicID, t3.graphicID, AVL.LINK_COLOR);
		}


		if (A.parent == null) {
			B.parent = null;
			this.treeRoot = B;
		}

		else {
			this.cmd("Disconnect", A.parent.graphicID, A.graphicID);
			this.cmd("Connect", A.parent.graphicID, B.graphicID, AVL.LINK_COLOR);
			if (A.isLeftChild()) {
				A.parent.left = B;
			}

			else {
				A.parent.right = B;
			}
			B.parent = A.parent;
			A.parent = B;
		}
		this.cmd("Disconnect", A.graphicID, C.graphicID);
		this.cmd("Disconnect", C.graphicID, B.graphicID);
		this.cmd("Connect", B.graphicID, A.graphicID, AVL.LINK_COLOR);
		this.cmd("Connect", B.graphicID, C.graphicID, AVL.LINK_COLOR);
		B.left = A;
		A.parent = B;
		B.right = C;
		C.parent = B;
		A.right = t2;
		C.left = t3;
		this.resetHeight(A);
		this.resetHeight(C);
		this.resetHeight(B);

		this.resizeTree();


	}
	insert(elem, tree) {
		this.cmd("SetHighlight", tree.graphicID, 1);
		this.cmd("SetHighlight", elem.graphicID, 1);

		if (elem.data < tree.data) {
			this.cmd("SetText", 0, elem.data + " < " + tree.data + ".  查询左子树");
		}

		else {
			this.cmd("SetText", 0, elem.data + " >= " + tree.data + ".  查询右子树");
		}
		this.cmd("Step");
		this.cmd("SetHighlight", tree.graphicID, 0);
		this.cmd("SetHighlight", elem.graphicID, 0);

		if (elem.data < tree.data) {
			if (tree.left == null) {
				this.cmd("SetText", 0, "空树, 插入元素");
				this.cmd("SetText", elem.heightLabelID, 1);

				this.cmd("SetHighlight", elem.graphicID, 0);
				tree.left = elem;
				elem.parent = tree;
				this.cmd("Connect", tree.graphicID, elem.graphicID, AVL.LINK_COLOR);

				this.resizeTree();
				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.left.x, tree.left.y);
				this.cmd("Move", this.highlightID, tree.x, tree.y);
				this.cmd("SetText", 0, "递归");
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);

				if (tree.height < tree.left.height + 1) {
					tree.height = tree.left.height + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
				}
			}

			else {
				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
				this.cmd("Move", this.highlightID, tree.left.x, tree.left.y);
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);
				this.insert(elem, tree.left);
				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.left.x, tree.left.y);
				this.cmd("Move", this.highlightID, tree.x, tree.y);
				this.cmd("SetText", 0, "递归");
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);

				if (tree.height < tree.left.height + 1) {
					tree.height = tree.left.height + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);

				}
				if ((tree.right != null && tree.left.height > tree.right.height + 1) ||
					(tree.right == null && tree.left.height > 1)) {
					if (elem.data < tree.left.data) {
						this.singleRotateRight(tree);
					}

					else {
						this.doubleRotateRight(tree);
					}
				}
			}
		}

		else {
			if (tree.right == null) {
				this.cmd("SetText", 0, "空树, 插入元素");
				this.cmd("SetText", elem.heightLabelID, 1);
				this.cmd("SetHighlight", elem.graphicID, 0);
				tree.right = elem;
				elem.parent = tree;
				this.cmd("Connect", tree.graphicID, elem.graphicID, AVL.LINK_COLOR);
				elem.x = tree.x + AVL.WIDTH_DELTA / 2;
				elem.y = tree.y + AVL.HEIGHT_DELTA;
				this.cmd("Move", elem.graphicID, elem.x, elem.y);

				this.resizeTree();


				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.right.x, tree.right.y);
				this.cmd("Move", this.highlightID, tree.x, tree.y);
				this.cmd("SetText", 0, "递归");
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);

				if (tree.height < tree.right.height + 1) {
					tree.height = tree.right.height + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
				}

			}

			else {
				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
				this.cmd("Move", this.highlightID, tree.right.x, tree.right.y);
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);
				this.insert(elem, tree.right);
				this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.right.x, tree.right.y);
				this.cmd("Move", this.highlightID, tree.x, tree.y);
				this.cmd("SetText", 0, "递归");
				this.cmd("Step");
				this.cmd("Delete", this.highlightID);
				if (tree.height < tree.right.height + 1) {
					tree.height = tree.right.height + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);


				}
				if ((tree.left != null && tree.right.height > tree.left.height + 1) ||
					(tree.left == null && tree.right.height > 1)) {
					if (elem.data >= tree.right.data) {
						this.singleRotateLeft(tree);
					}

					else {
						this.doubleRotateLeft(tree);
					}
				}
			}
		}


	}
	deleteElement(deletedValue) {
		this.commands = [];
		this.cmd("SetText", 0, "删除 " + deletedValue);
		this.cmd("Step");
		this.cmd("SetText", 0, " ");
		this.highlightID = this.nextIndex++;
		this.treeDelete(this.treeRoot, deletedValue);
		this.cmd("SetText", 0, " ");
		return this.commands;
	}
	treeDelete(tree, valueToDelete) {
		var leftchild = false;
		if (tree != null) {
			if (tree.parent != null) {
				leftchild = tree.parent.left == tree;
			}
			this.cmd("SetHighlight", tree.graphicID, 1);
			if (valueToDelete < tree.data) {
				this.cmd("SetText", 0, valueToDelete + " < " + tree.data + ".  查询左子树");
			}
			else if (valueToDelete > tree.data) {
				this.cmd("SetText", 0, valueToDelete + " > " + tree.data + ".  查询右子树");
			}

			else {
				this.cmd("SetText", 0, valueToDelete + " == " + tree.data + ".  找到需要删除的节点");
			}
			this.cmd("Step");
			this.cmd("SetHighlight", tree.graphicID, 0);

			if (valueToDelete == tree.data) {
				if (tree.left == null && tree.right == null) {
					this.cmd("SetText", 0, "删除叶子节点");
					this.cmd("Delete", tree.graphicID);
					this.cmd("Delete", tree.heightLabelID);
					if (leftchild && tree.parent != null) {
						tree.parent.left = null;
					}
					else if (tree.parent != null) {
						tree.parent.right = null;
					}

					else {
						this.treeRoot = null;
					}
					this.resizeTree();
					this.cmd("Step");

				}
				else if (tree.left == null) {
					this.cmd("SetText", 0, "要删除的节点没有左孩。\n将删除节点的父节点设置为删除节点的右子节点。");
					if (tree.parent != null) {
						this.cmd("Disconnect", tree.parent.graphicID, tree.graphicID);
						this.cmd("Connect", tree.parent.graphicID, tree.right.graphicID, AVL.LINK_COLOR);
						this.cmd("Step");
						this.cmd("Delete", tree.graphicID);
						this.cmd("Delete", tree.heightLabelID);
						if (leftchild) {
							tree.parent.left = tree.right;
						}

						else {
							tree.parent.right = tree.right;
						}
						tree.right.parent = tree.parent;
					}

					else {
						this.cmd("Delete", tree.graphicID);
						this.cmd("Delete", tree.heightLabelID);
						this.treeRoot = tree.right;
						this.treeRoot.parent = null;
					}
					this.resizeTree();
				}
				else if (tree.right == null) {
					this.cmd("SetText", 0, "要删除的节点没有右孩。\n将删除节点的父节点设置为删除节点的左子节点。");
					if (tree.parent != null) {
						this.cmd("Disconnect", tree.parent.graphicID, tree.graphicID);
						this.cmd("Connect", tree.parent.graphicID, tree.left.graphicID, AVL.LINK_COLOR);
						this.cmd("Step");
						this.cmd("Delete", tree.graphicID);
						this.cmd("Delete", tree.heightLabelID);
						if (leftchild) {
							tree.parent.left = tree.left;
						}

						else {
							tree.parent.right = tree.left;
						}
						tree.left.parent = tree.parent;
					}

					else {
						this.cmd("Delete", tree.graphicID);
						this.cmd("Delete", tree.heightLabelID);
						this.treeRoot = tree.left;
						this.treeRoot.parent = null;
					}
					this.resizeTree();
				}
				else // tree.left != null && tree.right != null
				{
					this.cmd("SetText", 0, "要删除的节点有两个子节点。\n在左侧子树中查找最大节点。");

					this.highlightID = this.nextIndex;
					this.nextIndex += 1;
					this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
					var tmp = tree;
					tmp = tree.left;
					this.cmd("Move", this.highlightID, tmp.x, tmp.y);
					this.cmd("Step");
					while (tmp.right != null) {
						tmp = tmp.right;
						this.cmd("Move", this.highlightID, tmp.x, tmp.y);
						this.cmd("Step");
					}
					this.cmd("SetText", tree.graphicID, " ");
					var labelID = this.nextIndex;
					this.nextIndex += 1;
					this.cmd("CreateLabel", labelID, tmp.data, tmp.x, tmp.y);
					this.cmd("SetForegroundColor", labelID, AVL.HEIGHT_LABEL_COLOR);
					tree.data = tmp.data;
					this.cmd("Move", labelID, tree.x, tree.y);
					this.cmd("SetText", 0, "将左子树的最大值复制到要删除的节点中。");

					this.cmd("Step");
					this.cmd("SetHighlight", tree.graphicID, 0);
					this.cmd("Delete", labelID);
					this.cmd("SetText", tree.graphicID, tree.data);
					this.cmd("Delete", this.highlightID);
					this.cmd("SetText", 0, "删除我们复制了其值的节点。");

					if (tmp.left == null) {
						if (tmp.parent != tree) {
							tmp.parent.right = null;
						}

						else {
							tree.left = null;
						}
						this.cmd("Delete", tmp.graphicID);
						this.cmd("Delete", tmp.heightLabelID);
						this.resizeTree();
					}

					else {
						this.cmd("Disconnect", tmp.parent.graphicID, tmp.graphicID);
						this.cmd("Connect", tmp.parent.graphicID, tmp.left.graphicID, AVL.LINK_COLOR);
						this.cmd("Step");
						this.cmd("Delete", tmp.graphicID);
						this.cmd("Delete", tmp.heightLabelID);
						if (tmp.parent != tree) {
							tmp.parent.right = tmp.left;
							tmp.left.parent = tmp.parent;
						}

						else {
							tree.left = tmp.left;
							tmp.left.parent = tree;
						}
						this.resizeTree();
					}
					tmp = tmp.parent;

					if (this.getHeight(tmp) != Math.max(this.getHeight(tmp.left), this.getHeight(tmp.right)) + 1) {
						tmp.height = Math.max(this.getHeight(tmp.left), this.getHeight(tmp.right)) + 1;
						this.cmd("SetText", tmp.heightLabelID, tmp.height);
						this.cmd("SetText", 0, "调整高度");
						this.cmd("SetForegroundColor", tmp.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
						this.cmd("Step");
						this.cmd("SetForegroundColor", tmp.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
					}



					while (tmp != tree) {
						var tmpPar = tmp.parent;
						// TODO:  Add extra animation here?
						if (this.getHeight(tmp.left) - this.getHeight(tmp.right) > 1) {
							if (this.getHeight(tmp.left.right) > this.getHeight(tmp.left.left)) {
								this.doubleRotateRight(tmp);
							}

							else {
								this.singleRotateRight(tmp);
							}
						}
						if (tmpPar.right != null) {
							if (tmpPar == tree) {
								this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tmpPar.left.x, tmpPar.left.y);

							}

							else {
								this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tmpPar.right.x, tmpPar.right.y);
							}
							this.cmd("Move", this.highlightID, tmpPar.x, tmpPar.y);
							this.cmd("SetText", 0, "正在备份 ...");

							if (this.getHeight(tmpPar) != Math.max(this.getHeight(tmpPar.left), this.getHeight(tmpPar.right)) + 1) {
								tmpPar.height = Math.max(this.getHeight(tmpPar.left), this.getHeight(tmpPar.right)) + 1;
								this.cmd("SetText", tmpPar.heightLabelID, tree.height);
								this.cmd("SetText", 0, "调整高度");
								this.cmd("SetForegroundColor", tmpPar.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
								this.cmd("Step");
								this.cmd("SetForegroundColor", tmpPar.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
							}

							//28,15,50,7,22,39,55,10,33,42,63,30 .
							this.cmd("Step");
							this.cmd("Delete", this.highlightID);
						}
						tmp = tmpPar;
					}
					if (this.getHeight(tree.right) - this.getHeight(tree.left) > 1) {
						if (this.getHeight(tree.right.left) > this.getHeight(tree.right.right)) {
							this.doubleRotateLeft(tree);
						}

						else {
							this.singleRotateLeft(tree);
						}
					}

				}
			}
			else if (valueToDelete < tree.data) {
				if (tree.left != null) {
					this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
					this.cmd("Move", this.highlightID, tree.left.x, tree.left.y);
					this.cmd("Step");
					this.cmd("Delete", this.highlightID);
				}
				this.treeDelete(tree.left, valueToDelete);
				if (tree.left != null) {
					this.cmd("SetText", 0, "递归");
					this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.left.x, tree.left.y);
					this.cmd("Move", this.highlightID, tree.x, tree.y);
					this.cmd("Step");
					this.cmd("Delete", this.highlightID);
				}
				if (this.getHeight(tree.right) - this.getHeight(tree.left) > 1) {
					if (this.getHeight(tree.right.left) > this.getHeight(tree.right.right)) {
						this.doubleRotateLeft(tree);
					}

					else {
						this.singleRotateLeft(tree);
					}
				}
				if (this.getHeight(tree) != Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1) {
					tree.height = Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
				}
			}

			else {
				if (tree.right != null) {
					this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.x, tree.y);
					this.cmd("Move", this.highlightID, tree.right.x, tree.right.y);
					this.cmd("Step");
					this.cmd("Delete", this.highlightID);
				}
				this.treeDelete(tree.right, valueToDelete);
				if (tree.right != null) {
					this.cmd("SetText", 0, "递归");
					this.cmd("CreateHighlightCircle", this.highlightID, AVL.HIGHLIGHT_COLOR, tree.right.x, tree.right.y);
					this.cmd("Move", this.highlightID, tree.x, tree.y);
					this.cmd("Step");
					this.cmd("Delete", this.highlightID);
				}


				if (this.getHeight(tree.left) - this.getHeight(tree.right) > 1) {
					if (this.getHeight(tree.left.right) > this.getHeight(tree.left.left)) {
						this.doubleRotateRight(tree);
					}

					else {
						this.singleRotateRight(tree);
					}
				}
				if (this.getHeight(tree) != Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1) {
					tree.height = Math.max(this.getHeight(tree.left), this.getHeight(tree.right)) + 1;
					this.cmd("SetText", tree.heightLabelID, tree.height);
					this.cmd("SetText", 0, "调整高度");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HIGHLIGHT_LABEL_COLOR);
					this.cmd("Step");
					this.cmd("SetForegroundColor", tree.heightLabelID, AVL.HEIGHT_LABEL_COLOR);
				}


			}
		}

		else {
			this.cmd("SetText", 0, "元素 " + valueToDelete + " 未找到，无法删除。");
		}

	}
	resizeTree() {
		var startingPoint = this.startingX;
		this.resizeWidths(this.treeRoot);
		if (this.treeRoot != null) {
			if (this.treeRoot.leftWidth > startingPoint) {
				startingPoint = this.treeRoot.leftWidth;
			}
			else if (this.treeRoot.rightWidth > startingPoint) {
				startingPoint = Math.max(this.treeRoot.leftWidth, 2 * startingPoint - this.treeRoot.rightWidth);
			}
			this.setNewPositions(this.treeRoot, startingPoint, AVL.STARTING_Y, 0);
			this.animateNewPositions(this.treeRoot);
			this.cmd("Step");
		}

	}
	setNewPositions(tree, xPosition, yPosition, side) {
		if (tree != null) {
			tree.y = yPosition;
			if (side == -1) {
				xPosition = xPosition - tree.rightWidth;
				tree.heightLabelX = xPosition - 20;
			}
			else if (side == 1) {
				xPosition = xPosition + tree.leftWidth;
				tree.heightLabelX = xPosition + 20;
			}

			else {
				tree.heightLabelX = xPosition - 20;
			}
			tree.x = xPosition;
			tree.heightLabelY = tree.y - 20;
			this.setNewPositions(tree.left, xPosition, yPosition + AVL.HEIGHT_DELTA, -1);
			this.setNewPositions(tree.right, xPosition, yPosition + AVL.HEIGHT_DELTA, 1);
		}

	}
	animateNewPositions(tree) {
		if (tree != null) {
			this.cmd("Move", tree.graphicID, tree.x, tree.y);
			this.cmd("Move", tree.heightLabelID, tree.heightLabelX, tree.heightLabelY);
			this.animateNewPositions(tree.left);
			this.animateNewPositions(tree.right);
		}
	}
	resizeWidths(tree) {
		if (tree == null) {
			return 0;
		}
		tree.leftWidth = Math.max(this.resizeWidths(tree.left), AVL.WIDTH_DELTA / 2);
		tree.rightWidth = Math.max(this.resizeWidths(tree.right), AVL.WIDTH_DELTA / 2);
		return tree.leftWidth + tree.rightWidth;
	}
	disableUI(event) {
		this.insertField.disabled = true;
		this.insertButton.disabled = true;
		this.deleteField.disabled = true;
		this.deleteButton.disabled = true;
		this.findField.disabled = true;
		this.findButton.disabled = true;
		this.printButton.disabled = true;
	}
	enableUI(event) {
		this.insertField.disabled = false;
		this.insertButton.disabled = false;
		this.deleteField.disabled = false;
		this.deleteButton.disabled = false;
		this.findField.disabled = false;
		this.findButton.disabled = false;
		this.printButton.disabled = false;
	}
}



// Various constants

AVL.HIGHLIGHT_LABEL_COLOR = "#FF0000"
AVL.HIGHLIGHT_LINK_COLOR = "#FF0000"

AVL.HIGHLIGHT_COLOR = "#007700"
AVL.HEIGHT_LABEL_COLOR = "#007700"


AVL.LINK_COLOR = "#007700";
AVL.HIGHLIGHT_CIRCLE_COLOR = "#007700";
AVL.FOREGROUND_COLOR = "0x007700";
AVL.BACKGROUND_COLOR = "#DDFFDD";
AVL.PRINT_COLOR = AVL.FOREGROUND_COLOR;

AVL.WIDTH_DELTA = 50;
AVL.HEIGHT_DELTA = 50;
AVL.STARTING_Y = 50;

AVL.FIRST_PRINT_POS_X = 50;
AVL.PRINT_VERTICAL_GAP = 20;
AVL.PRINT_HORIZONTAL_GAP = 50;
AVL.EXPLANITORY_TEXT_X = 10;
AVL.EXPLANITORY_TEXT_Y = 10;



class AVLNode {
	constructor(val, id, hid, initialX, initialY) {
		this.data = val;
		this.x = initialX;
		this.y = initialY;
		this.heightLabelID = hid;
		this.height = 1;

		this.graphicID = id;
		this.left = null;
		this.right = null;
		this.parent = null;
	}
	isLeftChild() {
		if (this.parent == null) {
			return true;
		}
		return this.parent.left == this;
	}
}